Fig. 5. Representative recordings from electro-olfactogram (EOG) cross-adaptation experiments recorded prior to (i), during (ii) and after (iii) adaptation to (A) 1 mmol l^–1 glutaric acid (a deaminated analog of glutamate; pK_a=4.34 and 5.22) and (B) 1 mmol l^–1 L-glutamate (a negatively charged amino acid). The adapting solution is underlined. C, CFTW control; Glt, glutaric acid; Glu, L-glutamate; Arg, 0.1 mmol l^–1 L-arginine; Put, 10 µmol l^–1 putrescine; Cad, 10 µmol l^–1 cadaverine; Spe, 3 µmol l^–1 spermine.